This is a continuation of a cooperative inter-institutional study of cancer in children, utilizing multi-disciplinary approach to treatment of those types of cancer which are suited for scientific analysis in a reasonable period of time. The studies are designed to provide answers to questions concerning optimum management, and at the same time provide the individual institutions with the added strengths to supply their communities with a referral center for childhood cancer. At the time of writing, there are 11 active protocols dealing with leukemia and 27 dealing with solid tumors including Phase II studies. The principal protocol for ALL/AML is designed to determine the relative importance of front-end factors in prognosis, with randomized increased therapy during maintenance for those with known poor prognostic findings. The present AML protocol is an effort to improve survival and duration of remission in childhood AML by combining the two best therapies from CCSG 241 and CCSG 102. Specific protocols currently being used are those for neuroblastoma, Stage III and IV; histiocytosis; retinoblastoma, unilateral and extraocular; brain tumors; osteogenic sarcoma; non-Hodgkin's lymphoma and ovarian tumors. On an intergroup basis, there are active protocols for rhabdomyosarcoma, Ewing's tumor both non-metastatic and metastatic, Hodgkin's disease and Wilms' tumor. Protocols being formulated and finalized are for bilateral retinoblastoma, brain tumors, nasopharyngeal carcinoma, and hepatoma. In addition, ongoing Phase II protocols utilize a succession or combination of new therapeutic agents such as Vindesine, galactitol, Azapicyl, Prednimustine, beta-TGdR, cis-platinum, Poly I:Poly C and hexamethylmelamine.